The use of normal and abnormal embryology as an experimental model to determine those factors leading to regeneration of flexor synovial tendons is continuing to be used in this grant. The failure of synovial differentiation in paralyzed chicken embryos has led to the choice of early motion as an inducer of regeneration. However, additional studies will continue to be made to determine if passive motion in these paralyzed chicks can cause differentiation. The failure of suturing techniques, in the past year of the grant proposal, to allow both active and passive motion requires that additional studies on the biomechanical, and evaluation of the presently used suture techniques, and the developing of new suture techniques is indicated. The study will continue on evaluating the effects of early motion, both passive and active, in the chick as a model system to prove this theory conclusively. As well as the above applied studies, basic investigations will continue on chick embryos and tendon organ culture. Specific emphasis will be placed on the effects of stress and motion on the tendon cells and their products of synthesis, collagen and other ground substances. BIBLIOGRAPHIC REFERENCE: "Biomechanical Effects of Early Passive Motion Upon Repaired Flexor Tendons." A. B. LaVigne and D. M. Chaplin. Proceedings 22nd Annual Orthopaedic Research Society, January 1976.